Module#initialize_copy allows to change the superclass of a class

You can abuse (({Module#initialize_copy})) to change the superclass of a class, because of this line of code in (({rb_mod_init_copy})):

RCLASS_SUPER(clone) = RCLASS_SUPER(orig);

(({Class#initialize_copy})) does perform some checks to stop you calling (({#initialize})) on an already initialized class, but this can be subverted by redefining it to call (({super})) from Ruby-land.